L’Antiquaire, tête en l’air
Recover Information
In this challenge, we have access to a memorendum.txt file. This file contains hex text. I tried decoding it using an online tool and find two links:
What is IPFS
The URL https://shorturl.ac/mysecretpassword is a … You guessed what… And the interesting part is /ipfs/bafybeia5g2umnaq5x5bt5drt2jodpsvfiauv5mowjv6mu7q5tmqufmo47i/metadata.json.
The InterPlanetary File System (IPFS) is a protocol, hypermedia and file sharing peer-to-peer network for storing and sharing data in a distributed file system. IPFS uses content-addressing to uniquely identify each file in a global namespace connecting IPFS hosts. IPFS can among others replace the location based hypermedia server protocols HTTP and HTTPS to distribute the World Wide Web.
When looking how to access IPFS files, we get to this website where we can see how to access IPFS on the web:
Access our first IPFS
We then go to the URL https://ipfs.io/ipfs/bafybeia5g2umnaq5x5bt5drt2jodpsvfiauv5mowjv6mu7q5tmqufmo47i/metadata.json and we found the JSON file:
We are given another IPFS link ipfs://bafybeic6ea7qi5ctdp6s6msddd7hwuic3boumwknrirlakftr2yrgnfiga/mystere.png:
If you don’t specify a file at the end of the IPFS address, you will see all the files shared on this IPFS.
What is Sepolia?
I first thought that this was the wallet of a certain user… But didn’t find anything. I then typed Sepolia on my browser and I found this:
When I go to this website, I enter the ETH address 0x96C962235F42C687bC9354eDac6Dfa6EdE73C188:
We can see that this blockchain has a contract. And when we head down to the Constructor Arguments section, we can see the flag:
And we validate this challenge with 404CTF{M3M3_P45_13_73MP5_D3_53CH4UFF3r_QU3_C357_D3J4_F1N1!}